android_os_ParcelFileDescriptor.cpp revision b1a7ffef3a0007b6991b8338460f6aac8cbb11e8 
1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17//#define LOG_NDEBUG 0
18
19#include "JNIHelp.h"
20
21#include <fcntl.h>
22#include <sys/stat.h>
23#include <stdio.h>
24
25#include <utils/Log.h>
26
27#include <android_runtime/AndroidRuntime.h>
28
29namespace android
30{
31
32static struct file_descriptor_offsets_t
33{
34    jclass mClass;
35    jmethodID mConstructor;
36    jfieldID mDescriptor;
37} gFileDescriptorOffsets;
38
39static struct socket_offsets_t
40{
41    jfieldID mSocketImpl;
42} gSocketOffsets;
43
44static struct socket_impl_offsets_t
45{
46    jfieldID mFileDescriptor;
47} gSocketImplOffsets;
48
49static struct parcel_file_descriptor_offsets_t
50{
51    jclass mClass;
52    jfieldID mFileDescriptor;
53} gParcelFileDescriptorOffsets;
54
55static jobject android_os_ParcelFileDescriptor_getFileDescriptorFromSocket(JNIEnv* env,
56    jobject clazz, jobject object)
57{
58    jobject socketImpl = env->GetObjectField(object, gSocketOffsets.mSocketImpl);
59    jobject fileDescriptor = env->GetObjectField(socketImpl, gSocketImplOffsets.mFileDescriptor);
60    jint fd = env->GetIntField(fileDescriptor, gFileDescriptorOffsets.mDescriptor);
61    jobject fileDescriptorClone = env->NewObject(gFileDescriptorOffsets.mClass,
62        gFileDescriptorOffsets.mConstructor);
63    if (fileDescriptorClone != NULL) {
64        env->SetIntField(fileDescriptorClone, gFileDescriptorOffsets.mDescriptor, dup(fd));
65    }
66    return fileDescriptorClone;
67}
68
69static jint getFd(JNIEnv* env, jobject clazz)
70{
71    jobject descriptor = env->GetObjectField(clazz, gParcelFileDescriptorOffsets.mFileDescriptor);
72    if (descriptor == NULL) return -1;
73    return env->GetIntField(descriptor, gFileDescriptorOffsets.mDescriptor);
74}
75
76static jlong android_os_ParcelFileDescriptor_getStatSize(JNIEnv* env,
77    jobject clazz)
78{
79    jint fd = getFd(env, clazz);
80    if (fd < 0) {
81        jniThrowException(env, "java/lang/IllegalArgumentException", "bad file descriptor");
82        return -1;
83    }
84
85    struct stat st;
86    if (fstat(fd, &st) != 0) {
87        return -1;
88    }
89
90    if (S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)) {
91        return st.st_size;
92    }
93
94    return -1;
95}
96
97static jlong android_os_ParcelFileDescriptor_seekTo(JNIEnv* env,
98    jobject clazz, jlong pos)
99{
100    jint fd = getFd(env, clazz);
101    if (fd < 0) {
102        jniThrowException(env, "java/lang/IllegalArgumentException", "bad file descriptor");
103        return -1;
104    }
105
106    return lseek(fd, pos, SEEK_SET);
107}
108
109static const JNINativeMethod gParcelFileDescriptorMethods[] = {
110    {"getFileDescriptorFromSocket", "(Ljava/net/Socket;)Ljava/io/FileDescriptor;",
111        (void*)android_os_ParcelFileDescriptor_getFileDescriptorFromSocket},
112    {"getStatSize", "()J",
113        (void*)android_os_ParcelFileDescriptor_getStatSize},
114    {"seekTo", "(J)J",
115        (void*)android_os_ParcelFileDescriptor_seekTo}
116};
117
118const char* const kParcelFileDescriptorPathName = "android/os/ParcelFileDescriptor";
119
120int register_android_os_ParcelFileDescriptor(JNIEnv* env)
121{
122    jclass clazz;
123
124    clazz = env->FindClass("java/net/Socket");
125    LOG_FATAL_IF(clazz == NULL, "Unable to find class java.net.Socket");
126    gSocketOffsets.mSocketImpl = env->GetFieldID(clazz, "impl", "Ljava/net/SocketImpl;");
127    LOG_FATAL_IF(gSocketOffsets.mSocketImpl == NULL,
128        "Unable to find impl field in java.net.Socket");
129
130    clazz = env->FindClass("java/net/SocketImpl");
131    LOG_FATAL_IF(clazz == NULL, "Unable to find class java.net.SocketImpl");
132    gSocketImplOffsets.mFileDescriptor = env->GetFieldID(clazz, "fd", "Ljava/io/FileDescriptor;");
133    LOG_FATAL_IF(gSocketImplOffsets.mFileDescriptor == NULL,
134                 "Unable to find fd field in java.net.SocketImpl");
135
136    clazz = env->FindClass("java/io/FileDescriptor");
137    LOG_FATAL_IF(clazz == NULL, "Unable to find class java.io.FileDescriptor");
138    gFileDescriptorOffsets.mClass = (jclass) env->NewGlobalRef(clazz);
139    gFileDescriptorOffsets.mConstructor = env->GetMethodID(clazz, "<init>", "()V");
140    gFileDescriptorOffsets.mDescriptor = env->GetFieldID(clazz, "descriptor", "I");
141    LOG_FATAL_IF(gFileDescriptorOffsets.mDescriptor == NULL,
142                 "Unable to find descriptor field in java.io.FileDescriptor");
143
144    clazz = env->FindClass(kParcelFileDescriptorPathName);
145    LOG_FATAL_IF(clazz == NULL, "Unable to find class android.os.ParcelFileDescriptor");
146    gParcelFileDescriptorOffsets.mClass = (jclass) env->NewGlobalRef(clazz);
147    gParcelFileDescriptorOffsets.mFileDescriptor = env->GetFieldID(clazz, "mFileDescriptor", "Ljava/io/FileDescriptor;");
148    LOG_FATAL_IF(gParcelFileDescriptorOffsets.mFileDescriptor == NULL,
149                 "Unable to find mFileDescriptor field in android.os.ParcelFileDescriptor");
150
151    return AndroidRuntime::registerNativeMethods(
152        env, kParcelFileDescriptorPathName,
153        gParcelFileDescriptorMethods, NELEM(gParcelFileDescriptorMethods));
154}
155
156}
157